By now it is plain what is happening to Chris Johnson, and what has happened to many running backs this offseason.

The three-time Pro Bowl back has been devalued, his 28-year-old legs being viewed with about the same trepidation and suspicion as the uneven ones on a wobbly table. Maybe they can be managed with some care, but you're probably going to want to move on pretty quickly.

Schein: Chris Johnson's NFL future

Where have you gone, CJ2K?
Adam Schein says Chris Johnson still has
value --
IF the former star can get his mind right.
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There are special circumstances for Johnson, who was released by the Tennessee Titans one week ago after the team couldn't find a trade partner. He is more of an outside runner. So, ideally, he should go to a team that has good offensive tackles. But eventually, Johnson will be signed (although likely not for big money). Even though running backs famously decline at his age with as much swiftness as they once tore through defenses, Johnson -- whose breathtaking speed still holds the NFL Scouting Combine record in the 40-yard dash -- retains the promise of a breakaway play. There are enough teams -- like the New York Jets, one of the most logical destinations for him -- that could use him to give desperately needed burst even if that explosiveness comes only about as frequently as a backyard firecracker.

A personnel executive from one team said that Johnson's long wait for a new job is likely as much about Johnson in particular as it is about how the game is played today.

"I think it could be both," he said. "But also the guy was making high money, and I'd bet his asking price was too high initially and now he's realizing his market isn't there anymore."

The cold shoulder Johnson has received, though, says even more about the big picture in football, even beyond the NFL. This isn't about Johnson or veteran running backs who have endured heavy workloads. This is about the inexorable diminution of the running game itself and all the parts that go with it.

There wasn't a running back taken in the first round of the 2013 NFL Draft and there almost certainly won't be one taken next month either -- but it goes much further than that. The result is that even those who enviously watch the Seattle Seahawks and San Francisco 49ers run their way to the very top of the NFL might not be able to find the pieces to emulate them, even if they bucked every trend in the game to try.

When Gil Brandt was working as a personnel maven for the Dallas Cowboys, team president Tex Schramm walked into his office one night after the first week of games in 1977. Schramm was on the Competition Committee then, and his question to Brandt was loaded with implications: "Did you see the scoring this week?" Brandt had seen it and what it showed was a dearth of touchdowns. Nine teams had scored seven points or fewer.

By the next year, the committee had put forward rules changes that have shaped everything about football since, from the contracts professional quarterbacks receive to how youth football is played on the school yard. Offensive linemen were allowed to extend their arms in pass blocking and defenders could not engage a receiver after five yards. The outsize passing numbers, the 7-on-7 football leagues that now dominate the youth game -- they all spring from those rules put in place that year.

The change was nearly immediate. In 1977, NFL teams averaged 25 pass attempts and 37.4 rushes per game. By 1980, it was 30.6 and 32.1. By 1984, teams averaged more passes than runs, and the NFL has not looked back since.

One perhaps unintended consequence was that pass protection became the primary focus of offensive linemen, in many cases to the near exclusion of run blocking. Big, tall players with long arms -- who perhaps were too short to be basketball power forwards -- were funneled toward the offensive line, where their reach and height made them better suited for pass protection than for the lower-to-the-ground run blocking. And when colleges -- and then high schools -- abandoned their traditional running games to follow the NFL toward the pass, the cycle was complete and run blocking was largely washed out of the system.

Contemporary college linemen so rarely run block that they are difficult to evaluate. Paul Alexander, the longtime Cincinnati Bengals offensive line coach, told me five years ago that to evaluate O-line prospects, NFL coaches and scouts will often only watch goal-line tape because it is more likely to involve run plays than passes. And NFL offensive line coaches now must teach run blocking to those who have never performed it.

"There's guys in the league who can pass block but can't run block," Alexander told me then, for a story in The New York Times. "There is nobody playing in the league who can run block but can't pass protect."

Chris Johnson through the years

Check out the best photos of Chris Johnson.

The consequence: There simply aren't enough offensive linemen proficient enough in run blocking to go around, and certainly not enough to power a league full of copycat teams who eye Seattle's success with Marshawn Lynch.

"There just aren't enough offensive linemen that are skilled enough to play with," Brandt said.

And so the cycle feeds itself. Whereas once the running game was dominant at the earliest entry points to the game -- it is, after all, still easier to hand off than to accurately throw, and the wishbone attack was still prevalent in college not all that long ago -- the pass has become such a focal point that the athletes who might once have been running backs are instead being moved to other positions, so that they too can flourish in the sophisticated offenses that are run at the high school levels. And, Brandt says, because college defenses are so fast and so sophisticated now, it makes it even harder for college offenses to run.

The end result is apparent in a quick look at the 2013 season. Teams averaged just 27.1 rushes per game, the lowest figure in recorded history, according to Pro-Football-Reference.com, which tracks the numbers back to 1932. Meanwhile, teams averaged 35.4 pass attempts per game, the most ever. And offenses averaged 23.4 points per game, another all-time high. The pressure to score, combined with the lack of resources to produce consistent and plentiful running attacks, almost certainly means the future Chris Johnsons of the world won't fare any better on the open market than he is -- even if some coaches long to exploit defenses that are getting progressively smaller and quicker to stop the pass.

Still, Johnson had a pretty good run, considering he eclipsed 2,000 yards in 2009. Adrian Peterson did it in 2012. But the historical evolution detailed above raises an obvious question: When will the NFL have another 2,000-yard rusher?

It seems foolish to declare that it will never happen again, no matter how much the talent and the rules tilt toward the pass. But it almost certainly will take an outlier of a running back who happens to fall into the perfect confluence of circumstances with his team to do it. It would take a coach willing to use a run-first offense, with a defense constructed to win close games, and likely with a middling -- or at least unproven -- quarterback. Ironically, that is how the Jets were constructed when they went to two consecutive AFC Championship Games under Rex Ryan. If they land Johnson, perhaps it will be the way they are built again.

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But a look at the statistics shows that a 2,000-yard rusher is going to be as rare as a three-yards-and-a-cloud-of-dust offensive coordinator. When Johnson and Peterson broke the 2,000-yard mark, they each averaged more than 20 attempts per game. In 2013, only one running back in the entire league did: Doug Martin of Tampa Bay. And that might only have been because he played in just the first six games before suffering a season-ending injury. Even the NFL's leading rusher -- LeSean McCoy, who plays in a Chip Kelly offense that easily led the league in rushing -- averaged just 19.6 carries. Marshawn Lynch, Seattle's workhorse back, averaged 18.8.

And those numbers are far greater than anything posted by the younger backs who received multi-year contracts in free agency this offseason. At 27, Toby Gerhart and Joique Bell are just one year younger than Johnson. But neither has absorbed the blows of a primary running back. Gerhart has logged only one season with more than 100 rushes, and last year he ran just 36 times. Bell had 166 rushes last year, but just 248 total in his NFL tenure.

Their careers will look much different than Johnson's, of course. As different as the landscape of the running game must look to Johnson right now.